Usage
Hydrochlorothiazide + Telmisartan is prescribed for the treatment of hypertension (high blood pressure) in patients whose blood pressure is not adequately controlled by monotherapy (either telmisartan or hydrochlorothiazide alone). This fixed-dose combination is not indicated for initial therapy. It is used to lower blood pressure, reducing the risk of fatal and nonfatal cardiovascular events, such as strokes and myocardial infarctions. It may also be used for other conditions as determined by your healthcare provider.
It’s pharmacological classifications are:
- Telmisartan: Angiotensin II Receptor Blocker (ARB)
- Hydrochlorothiazide: Thiazide Diuretic
Mechanism of Action: Telmisartan blocks the action of angiotensin II, a hormone that causes blood vessels to narrow. This blockade results in vasodilation (widening of blood vessels), lowering blood pressure. Hydrochlorothiazide increases the excretion of sodium and water by the kidneys, which also contributes to lower blood pressure.
Alternate Names
The combination is often referred to as telmisartan/hydrochlorothiazide or telmisartan/HCTZ.
Brand Names: Micardis HCT, PritorPlus, and various generic versions are available.
How It Works
Pharmacodynamics: Telmisartan exerts its antihypertensive effect by blocking the binding of angiotensin II to the angiotensin II type 1 (AT1) receptor. This prevents the vasoconstricting and aldosterone-secreting effects of angiotensin II. Hydrochlorothiazide increases the excretion of sodium and chloride in the urine, leading to diuresis (increased urine production) and a decrease in blood volume, both of which lower blood pressure.
Pharmacokinetics:
- Absorption: Telmisartan is rapidly absorbed after oral administration, while hydrochlorothiazide is well absorbed from the gastrointestinal tract.
- Metabolism: Telmisartan is mainly metabolized by glucuronidation to inactive metabolites. Hydrochlorothiazide is not extensively metabolized.
- Elimination: Telmisartan is primarily excreted in the feces via biliary excretion, with a small amount in urine. Hydrochlorothiazide is eliminated unchanged by the kidneys.
Dosage
Standard Dosage
Adults:
The initial dose is usually 40 mg telmisartan/12.5 mg hydrochlorothiazide once daily. If blood pressure is not adequately controlled, the dose may be increased to 80 mg telmisartan/12.5 mg hydrochlorothiazide or 80 mg telmisartan/25 mg hydrochlorothiazide once daily after 2 to 4 weeks. The maximum recommended dose is 160 mg telmisartan/25 mg hydrochlorothiazide daily.
Children:
The safety and efficacy in children have not been established, so the drug is not typically used in this population.
Special Cases:
- Elderly Patients: Initiate therapy at the lower end of the dosing range (40mg/12.5mg) and titrate as needed. Closely monitor renal function.
- Patients with Renal Impairment: Not recommended for patients with severe renal dysfunction (creatinine clearance less than 30 mL/min). Periodic monitoring of creatinine and electrolytes is needed in those with mild to moderate impairment. Dosage adjustments may be required.
- Patients with Hepatic Dysfunction: Not recommended for patients with severe hepatic dysfunction. In patients with mild to moderate liver dysfunction, the initial dose is usually 40 mg telmisartan/12.5 mg hydrochlorothiazide once daily.
- Patients with Comorbid Conditions: Careful monitoring is required in patients with diabetes, gout, lupus, skin cancer, heart failure, hepatic impairment, and electrolyte imbalance. Dosage adjustments may be required.
Clinical Use Cases
The combination is not typically used in settings like intubation, surgical procedures, mechanical ventilation, ICU use, or emergency situations. Its primary role is in the chronic management of hypertension.
Dosage Adjustments
Adjustments may be necessary depending on the patient’s response to therapy, renal or hepatic function, and comorbid conditions.
Side Effects
Common Side Effects:
Dizziness, upper respiratory tract infection, sinusitis, diarrhea, fatigue, influenza-like symptoms, nausea, back pain, and cough.
Rare but Serious Side Effects:
Hypotension (low blood pressure), angioedema (swelling of face, lips, tongue, or throat), syncope (fainting), renal impairment, hyperkalemia (high potassium levels), hyponatremia (low sodium levels), and allergic reactions.
Long-Term Effects:
Long-term effects are mostly related to untreated high blood pressure, which the medication aims to manage. Potential complications of the medication itself during long-term use include electrolyte disturbances, changes in lipid levels, and potential renal dysfunction.
Adverse Drug Reactions (ADR):
Serious ADRs require immediate medical attention and may include severe hypotension, angioedema, acute renal failure, and electrolyte disturbances.
Contraindications
- Hypersensitivity to telmisartan, hydrochlorothiazide, or sulfonamide-derived drugs.
- Pregnancy (second and third trimesters).
- Anuria (absence of urine production).
- Severe renal or hepatic impairment.
- Cholestasis, biliary obstructive disorders.
- Refractory hypokalemia, hypercalcemia.
- Concurrent use of aliskiren in patients with diabetes or moderate to severe renal impairment.
Drug Interactions
Hydrochlorothiazide + Telmisartan can interact with various medications, including:
- Other antihypertensive drugs: May have additive hypotensive effects.
- Lithium: Risk of increased lithium levels and toxicity.
- Digoxin: May increase digoxin levels.
- NSAIDs: May reduce the antihypertensive effect of telmisartan.
- Potassium-sparing diuretics, potassium supplements: May increase potassium levels.
- Alcohol: Additive effect in lowering blood pressure
- Cholestyramine or colestipol Take this product at least 4 hours before or 4-6 hours after these medications.
Pregnancy and Breastfeeding
- Pregnancy: Contraindicated in the second and third trimesters due to the risk of fetal harm. Should be discontinued as soon as pregnancy is detected.
- Breastfeeding: Not recommended, as hydrochlorothiazide is excreted in breast milk.
Drug Profile Summary
- Mechanism of Action: Telmisartan blocks angiotensin II receptors, causing vasodilation. Hydrochlorothiazide increases sodium and water excretion, lowering blood volume.
- Side Effects: Common: Dizziness, upper respiratory tract infection. Serious: Angioedema, hypotension, hyperkalemia.
- Contraindications: Pregnancy, anuria, hypersensitivity, severe renal/hepatic impairment.
- Drug Interactions: Lithium, digoxin, NSAIDs, other antihypertensives, alcohol.
- Pregnancy & Breastfeeding: Contraindicated in pregnancy, not recommended during breastfeeding.
- Dosage: Initial: 40 mg/12.5 mg once daily. Max: 160 mg/25 mg once daily. Adjust for renal/hepatic impairment.
- Monitoring Parameters: Blood pressure, potassium levels, renal function, electrolytes.
Popular Combinations
Other antihypertensive medications (e.g., calcium channel blockers, ACE inhibitors) can be used in combination with hydrochlorothiazide + telmisartan if blood pressure is not adequately controlled.
Precautions
- Monitor for hypotension, especially after the first dose or in patients with volume depletion.
- Monitor renal function and potassium levels regularly.
- Caution in patients with liver disease, gout, lupus, or diabetes.
- Avoid alcohol during treatment, which can increase the risk of low blood pressure.
- Advise patients about potential side effects such as dizziness and to avoid driving or operating machinery if affected.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Hydrochlorothiazide + Telmisartan?
A: The usual starting dose is 40 mg/12.5 mg once daily. This can be increased to a maximum of 160 mg/25 mg daily if necessary.
Q2: Can this medication be used during pregnancy?
A: No, it is contraindicated during the second and third trimesters of pregnancy.
Q3: What are the common side effects?
A: Common side effects include dizziness, upper respiratory tract infection, sinusitis, and diarrhea.
Q4: How does this combination work to lower blood pressure?
A: Telmisartan blocks angiotensin II receptors, and hydrochlorothiazide increases sodium and water excretion. These actions work synergistically to lower blood pressure.
Q5: Are there any dietary restrictions while taking this medication?
A: Patients should limit alcohol intake, as it can increase the risk of low blood pressure. They should also maintain adequate hydration and discuss with their doctor whether or not to restrict sodium in their diet.
Q6: How should patients with renal impairment be managed?
A: Patients with severe renal dysfunction (creatinine clearance less than 30 mL/min) should not take this medication. In those with mild to moderate impairment, renal function and potassium levels must be monitored closely. Dosage adjustments may be required.
Q7: Can this combination be used as the initial treatment for hypertension?
A: No, it is not recommended for initial therapy. Monotherapy (either telmisartan or hydrochlorothiazide alone) should be tried first.
Q8: Are there any specific contraindications I should be aware of?
A: Yes. The medication is contraindicated in pregnancy, hypersensitivity, severe renal or hepatic impairment, biliary obstructive disorders, anuria, and certain electrolyte imbalances. It should not be used concurrently with aliskiren in patients with diabetes or moderate to severe renal impairment.
Q9: What should I monitor in patients taking Hydrochlorothiazide + Telmisartan?
A: It’s crucial to monitor blood pressure, potassium and electrolyte levels, and renal function regularly, especially at the start of therapy or with dosage adjustments. Monitor signs of hypotension, fluid, or electrolyte imbalance.
